The present invention relates to a new and improved construction of a stepping or indexing mechanism for an encoding rotary or multi-position switch.
Generally speaking, the stepping or indexing mechanism of the present development is of the type comprising a symbol or numeric wheel arranged in a switch housing, broadly simply referred to as a character wheel, a switching or indexing element and a locking or latching device which essentially embodies a locking or latching wheel and at least one locking or latching lever which is mounted at one end in the switch housing and resiliently engages at its other end with the locking wheel.
In German Patent No. 1,186,124, published Jan. 28, 1965, there is disclosed an electrical rotary or multi-position switch having a locking or latching device containing a locking or latching wheel and two mirror-image symmetrically arranged locking or latching levers. With the heretofore known construction of the locking wheel the flanks of the locking cams possess a sawtooth-like curved configuration and there engage into the locking recesses of the locking wheel a semi-circular shaped projection or extension which is formed at the related locking lever. At the other end each locking lever possesses a semi-circular shaped recess into which engages a bearing or support portion mounted in the switch housing and constructed as a pivotable element. The locking levers are pressed by means of a respective compression or pressure spring, which are essentially supported at the switch housing, together with the thereat formed projection into the locking or latching recess. Upon actuation of the switch the locking lever together with its projection slides along the locking cam flank and at the same time such is deflected out of the locking or latching recesses.
With the heretofore known construction of rotary or multi-position switch the relatively complicated construction of the locking or latching lever, on the one hand, as well as the arrangement of the locking or latching levers, springs and the pivotal element, on the other hand, necessitates an increased number of working steps during the fabrication and assembly of the rotary switch. Additionally, this latching device in its existing construction is not suitable for use with a multi-position selector switch or thumbwheel switch, also referred to in the art as an encoding rotary or thumbwheel switch.
Other exemplary constructions of rotary switches have been disclosed, for instance, in French Patent No. 2,188,277, published Jan. 18, 1974, German Patent Publication No. 1,014,627, published Aug. 29, 1957, and U.S. Pat. Nos. 3,133,164; 3,195,358; 3,499,127; and 3,654,413.